When photosensitive photographic materials are employed in various sizes, from the viewpoint of ease of handling and space saving, the required amount is often taken from the material in a roll form and subsequently employed. Specifically, in the printing and plate making field, a large amount of materials employed are in the form of rolled film.
When the film is employed in such a manner, in terms of workability, a major problem is roll-set curl of the film. For example, problems occur such that during continuous cutting of the film employing an automatic roll cutter, when the roll-set curl is severe, cut film sheets do not pile well; when exposure is carried out upon bringing a sheet of film into contact with an original, insufficient contact and similar problems occur.
In recent years, along with the size reduction of apparatuses, the size of rolled film has tended to decrease, and the size of roll cores has also decreased. Film exhibiting less roll-set curl is thus highly desirable.
As methods to minimize this roll-set curl, for example, Japanese Patent Publication Open to Public Inspection No. 51-16358 proposes that as a method to minimize the roll-set curl of polyester film, thermoplastic film is subjected to thermal treatment at Tg-5.degree. C. to Tg-30.degree. C. for 0.1 to 1,500 hours. Further, Japanese Patent Publication Open to Public Inspection No. 6-35118 proposes that after subbing polyester film having Tg of 90 to 200.degree. C., the resulting film is subjected to thermal treatment at 50.degree. C. to Tg for 0.1 to 1,500 hours.
However, in these methods, thermal treatment at a relatively low temperature for a long period is required and is not efficient in terms of production. Furthermore, when a long roll of film is produced, it must be subjected to thermal treatment for a long period as an intermediate product in the wound-roll state and a problem occurs, such that roll-set curl is caused due to the diameter of the wound core. When it is employed to produce a silver halide photosensitive photographic material in the rolled state, problems occur such that the roll-set curl, previously caused by the above mentioned thermal process, makes it impossible to exhibit sufficient advantages.
These problems are not so serious for silver halide photosensitive photographic materials which are wound on a relatively small core, while they are particularly serious for those such as graphic art materials, etc. which are wound on a relatively large core.
Furthermore, when thermal treatment is carried out in the rolled state, the thermal treatment process has been limited due to problems such as the degradation of flatness, and adherence between contacting surfaces.